Electric Vehicle Regional Emissions & Demand Impacts Tool (EV-REDI)

EV-REDI (Electric Vehicle Regional Emissions and Demand Impacts) is an in-house tool for modeling multiple impacts of transportation electrification for specific states and provinces. With electric vehicles on the rise, there will be enormous opportunities for making transportation more sustainable and modernizing the electric grid. But in order to realize this potential, it will be necessary to plan ahead. More and more, states, cities, utilities, and regional authorities are seriously considering the impacts of futures in which electric vehicles play an increasingly important role in the transportation sector. Synapse’s EV model can help meet the need to quantify the impacts of increased EV penetration on electricity sales, greenhouse gas emissions, and avoided gasoline consumption for all 50 U.S. states, Washington D.C., and ten Canadian provinces. 

EV-REDI relies on high-resolution data from publicly available sources to assemble state- and province-specific information on the historical adoption of EVs and develop trajectories of future EV deployment. The tool can integrate with electric sector dispatch models to inform capacity expansion and hourly dispatch, such as Synapse’s M-SEM  (which can be used to develop a comprehensive picture of future emissions across all energy sectors), or AVERT  (an official EPA tool developed by Synapse) to examine high-resolution CO2 and criteria pollutant emission impacts on the electricity grid.

EV-REDI allows us to apply a technology adoption curve to existing historical trends to understand the impacts of EVs if current trends in adoption are sustained over time. Alternatively, EV-REDI can be used to analyze specified future levels of electric vehicle sales in absolute terms or in percentage terms, or set the total number of EVs (stock) in absolute terms or percentage terms. Under either approach, EV-REDI then quantifies both conventional and electric light-duty vehicle (LDV) sales and stock, and the resultant impacts on electricity sales, tailpipe emissions, gasoline consumption, and other metrics through 2050 (see Figure 1 for a comparison of EV sales projections from EV-REDI, relative to projections from several other organizations). For every state, EV-REDI accounts for:

  • State- and province-specific trends in light-duty vehicle stocks, sales, and driving patterns
  • Vehicle ownership lifetime
  • Vehicle miles travelled (VMT)
  • Changing efficiencies of both EVs and conventional vehicles
  • Changing trends in vehicle preferences
  • Distinctions between driving patterns of plug-in hybrid electric vehicles (PHEVs) and purely battery-powered electric vehicles (BEV)

Further studies of EVs will be needed to determine the full scope of this new technology’s impact on the energy system. For example, as EVs charge using the electric grid, they may increase CO2 emissions from the electric sector that may partially offset the emissions avoided through decreased use of gasoline. The impacts on electricity customers are also an important element to understand. Greater electricity sales due to EVs may help to exert downward pressure on rates as the fixed costs of the grid are spread across more kilowatt-hours. However, this effect will be uneven and will depend on state- and province-specific penetration levels, as well as where and when EV charging occurs.

As the deployment of electric vehicles increases, policymakers will need to contend with the hourly impacts of EVs on the grid, including considerations relating to peak demand and rate design. Synapse has studied the grid impacts of EVs to date in California and is developing a series of reports on best practices in EV rate design.